The C8 sealed the fate of Unitron, then in the mid and later 80's AP and cheap Dobs did in what was left of the big EQ mounted Newts.
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Posted 05 November 2018 - 07:24 PM
The C8 sealed the fate of Unitron, then in the mid and later 80's AP and cheap Dobs did in what was left of the big EQ mounted Newts.
Posted 16 November 2018 - 02:44 PM
November 15, 2018
Seeing was predicted to be very good tonight but the image I am getting is plagued by the constant shimmering of the atmosphere. It is far better than it was three nights back when I could not get sharp focus on the moon no matter how hard I tried. Nothing that night but MUSHY crap. I was worried that my collimation was pathetically off but tonight clarified that. I need to get a fan system up and running to see if what I am dealing with is due to tube currents or seeing. From pretty careful looking I am almost certain that the bulk of the issue is “seeing” with a tiny bit added by tube currents. Still plenty of reason to eliminated them. The impression one gets is that a sharp and nearly perfect image is hidden behind the residual shimmering. The scope has been out for an hour or more but the temp is still falling so I doubt if the mirror has hit equilibrium yet. The image looked more stable just before sunset, pretty normal actually. The dropping temps start just after sundown and continue for a number of hours. The hourly forecast seems to indicate that the temperature will stabilize around midnight (37degrees) and hold reasonably steady - varying from 37 to 34 degrees - until 4:00AM or so. I intend to get up around 2:00 or 3:00 and spend some time with Orion after the moon has set.
I did a few checks to see how the collimation is and all say it is very well aligned. Vega was beautiful and moved in and out of focus with very similar “bullseye” patterns and the secondary quite well centered. Just for kicks I swung up to the double-double and both pairs were easily separated at 150x with the 12mm Docter. Swinging back to the moon I was watching the small crater complex between Catharina and Rupes Altai. Even with the shimmering I could see a wealth of fine detail popping in and out of sharp focus just south of Catharina and east of crater Polybius.
The moon this evening matches the “9-day old Moon” page in the Legault/Brunier Atlas. Plato is amazing – a huge dark shadow-filled basin surrounded by a brightly illuminated rim. It is literally sitting on the terminator and there is what appears to be a high point on its eastern edge that is like a spotlight it is so bright. I have never really looked at Plato when it is illuminated as it is tonight, nor have I ever paid as much attention to the bumpy features bordering Mare Imbrium near Montes Recti and Montes Teneriffe. Lots of relief features normally overlooked due to the pull of an illuminated Plato. Beautiful!
One other area that keeps pulling my eye toward it is the Rima Hyginus region. In more stable moments it is a brilliant cleft across a plain with the central crater clear as day and lots of fine internal detail. Unfortunately the seeing keeps shifting.
M13 is low in the west but still a marvelous sight. I think I may head to bed and see if I can drag myself out around 2:00…..
There is no question in my mind that the old Cave is a stunning performer. All it needs is stable seeing and it should run away from everything!
Back out a little after 4:00 AM. The sky seemed to have stabilized quite a bit but without the Moon or a major planet there was no way to check the level of the scope’s planetary performance. One of the reasons I left the scope out was to see how it did on M42 – in a word: STUNNING! The big mrror really delivered and with a range of eyepieces – 10mm XW, 12mm Docter, 20mm XW and 30mm XW the nebula was a study in fine detail with knots and filaments galore! Bluish- grey in color but so much fine detail I found I was simply staring! Hard to say which view I enjoyed most but the 20mm and 30mm XWs really shine on M42! Maybe a slight edge to the 20mm this morning.
Initially the seeing seemed to interfere with sharp focus and it was mixed a bit with high clouds moving across the sky. Leo was pretty much lost in them as was anything to the east, but Orion, Auriga and Gemini were in a large hole. I used Rigel to check collimation and it was very good. With a 10mm XW in place (190x) I could easily see the “E” and not quite so easily the “F” components of the Trapizum. With a 20mm XW (95x) I could still see the “E” consistently, and the”F” fleetingly.
Since it was pretty out, I swung the scope up to locate M78. Did so pretty quickly - faint and small; not much to look at but the 12.75” mirror hauled it in nicely. Same with M1, which I also found quickly once I had consulted the Telerad sky charts….
Went back out around 5:00 and as it was still dark I took a quick look at M37 and M38 in Auriga through the 30mm XW. M37 was simply beautiful. It reminded me of a “failed” globular cluster, one that did not quite get its act together to contract into a pronounced ball. M38 was also very pretty, with a small knot of stars catching my attention. Almost like a distant, small globular tucked into the edge of the open cluster.
Impressions: I need to rig a cooling fan to see if that cures some of the instability in lunar and planetary images. One thing I am realizing is how much I like seeing the entire sky when sitting out between “sessions”. One point for a rolloff!
working on cooling fan pattern....
Posted 17 November 2018 - 08:23 AM
Its probably the seeing my friend. When I first looked through that scope my jaw shattered against the floor! Cratelets within cratelets in Plato and the fine hairline on the floor of Alpine Rille was obvious. For cooling(which isn't a big issue here) I would put the scope horizontally then put a 20" fan up to the front of the scope sucking air out. Usually 30 minutes was enough.
Posted 17 November 2018 - 11:24 AM
No question the seeing is the issue. The weather in Central Oregon seems to come mostly from the west dropping down the Cascades. A fellow amateur here said it is like a wave of air breaking as it cascades (pun?) down the east slope of the mountains. However, when the weather direction shifts seeing can become excellent. Years back I had an wonderful Cave 8” f/8 and added a rear cooling fan. Planetary images definitely benefitted from the airflow and vibration was never an issue. Since it is an easy “fix” I will add one to the Cave/Paul and see how much it helps.
While I have had it out enough to have had some super planetary images, I have not yet had truly excellent seeing. The optics in in this scope are essentially perfect, .995 Strehl. Add the Quartz substrate and, well as you said so well, pad the floor because your jaw is going to drop!
Posted 18 November 2018 - 11:23 PM
Reasonable seeing tonight so I have the TEC200ED and Cave out and am waiting for the Cave to cool. Looking at the moon it is a match for the “11-day-old Moon" in Legault/Brunier . My primary target at the moment is Gassendi and there is no question that the TEC is turning in a better image. I am 90% sure it is cooling and tube currents in the big Cave and can tell it might pull the TEC if the mirror can stabilize. Both images have some shimmering, but the TEC hits far sharper focus. More cool down time is in order.
I decided to let the scopes sit out and try again after dinner – what a difference!! The mirror in the Cave was obviously still cooling when I stopped earlier but now that it has had more time to close in on ambient temperature it is turning in amazing images. I can actually see fine detail within Gassendi better in the Cave – and by better I mean BOTH finer detail and sharper detail in the rilles and faults on the crater floor. Well, maybe sharpness is a push, but resolution is greater in the Cave. Nancy came out and looked through both and said, “The blue one (Cave) is better and the moon much brighter. The blue one is always better.” I would not have believed it if I had not seen the images, side-by-side myself. I am running a 10mm XW in the Cave (185x) and a 9mm Nagler T-6 (200x) in the TEC. I just happen to have a second 9mm Nagler T-6 which will put the Cave at 210x so…..
Man it is hard to call it now! There is still a bit of atmospheric “shimmering” and you have to wait for fleeting moments of best seeing but when you do there are a few really fine features I can definitely see better in the Cave than in the TEC. One is a small ridge just outside the Gassendi wall, a small thin, jagged line of light suspended above total darkness that is simply easier to see in the Cave than the TEC. There is also what appears to be a “triangular enclosure” on the east side of Gassendi containing a small wedge-shaped ridge. It looks like a closed off section of the crater wall in the present lighting though in Rukl’s (Map 52) it is clearly not. However, there is a wealth of detail near the wedge-shaped ridge that the Cave shows more consistently. I can see it in the TEC too, but easier in the Cave. I think these two scopes are so good optically that I am simply seeing the greater resolving power of the larger scope. What is fascinating is that there is no “refractor-like” comparison; they are simply indistinguishable in terms of sharpness and resolution and with the same eyepiece running just at slightly more than a 10x difference in magnification. The mirror on the Cave is stunning. Years back I did a similar comparison between the 8” F/12 D&G and a 12.5” Portaball with Zambuto optics. I found them so close I felt it was a tie though the D&G had just a trace of residual color, a blue tinge around lunar detail. The TEC has NONE, it is a superb system, but the Cave is just a tad better. This time it is not a tie, it is very close but the larger scope is showing more. And brighter.
Ergonimics go to the refractor. I am standing on the bottom rung of a three-step ladder when viewing through the Cave and can easily be seated while using the TEC. Plus, a binoviewer is a cinch to add to the TEC while it is a bit more of an ordeal with the Cave. And though the Schaefer mount is a world better than the old Cave mounts I have owned in terms of stability, the HGM-200 with the Gemini 2 system is so much easier to use. Cost? The Cave is far and away the winner! I have roughly $5000 in it including the mount and pier. Closer to five times that in the TEC and HGM-200. And one feature that you cannot put a dollar value on – this scope was envisioned by Dr Henry Paul who entrusted Tom Cave to bring it to reality. Cave did exactly that and turned out what is arguably his finest mirror ever. He had it tested by the head optician at Mt Wilson/Palomar before he deemed it ready to send to Dr Paul. Dr Paul used it for years before it went through a series of owners, most of whom are friends, finally ending up with me. And along the way Carl Zambuto evaluated it as well. Lots of history in this fine optic!
Posted 20 November 2018 - 10:39 AM
The first time it happened I was out with a C102F and went to bed planning to get up around 2:00 AM. Slept right past 2:00 and the next morning I found the scope coated in ice. For a few moments I was worried I had done something wrong, harmed the scope in some way. Now, years later and many more similar experiences wiser, I know the scopes can take it. But, I NEVER drag them back into a far warmer place; rather I let them sit in the garage to warm slowly. My theory is that I own them to use them and that means - especially here in central Oregon in winter when we get some of our best viewing - subjecting them to very cold temperatures.
Posted 21 November 2018 - 06:51 PM
OK Rolo, now I am ready for another round with the TEC200ED. Each time I think about the last one it is the added structure in M42 that stands out.
Posted 21 November 2018 - 10:50 PM
Larry, 4.5 more inches of superior optics may be more than the TEC200 can compete with...
Posted 21 November 2018 - 11:59 PM
I really enjoyed your write ups Larry. What a great project and bit of history.
I have the honor of having, using and comparing a fine 11" F7 CZ based newt and a TEC 200ED on a regular basis. Your comments match mine pretty good. Mine is a closer horse race though due to the smaller aperture of the CZ/Parallax newt. One advantage the TEC has is the ability to "come on line" a bit sooner than the newt especially for fine, high power solar system viewing. This has advantages right before and after sunset around here as the upper atmosphere can, at times, be very calm then. However, the newt does catch up. But, for me, there is that something to the images that the big TEC serves up that speaks to my heart while the newt speaks to my more analytical side.
I sometimes feel I have to choose between them. But, fortunately, I do not have to make a choice and can enjoy both.
For that, I am very thankful.
Edited by Jeff B, 22 November 2018 - 12:17 AM.
Posted 22 November 2018 - 08:25 AM
I have followed your posts about the TEC200ED for a while now and they are part of the reason I bought this one. And I would have to agree with everything you said. Over the years I have always found I prefer refractors for a number of reasons, not the least of which is the closed tube and freedom from tube currents. Plus seated viewing and what appears to be faster cool down. Rolo owned the Paul-Cave before me and his evaluation is spot on too - the big Cave with its quartz mirror and stunning figure is a killer. When I had them out a few nights ago it was fascinating seeing the old Cave pull away from the TEC. To be honest I was not expecting that to happen, but it took a long time for cooling and a bit of patience before it all came together. Unfortunately Saturn and Jupiter were not able to attend our little session, but the Moon filled in nicely. What really separated them was the knots and filaments in M42 - they were very nice in the TEC, but appeared 3-D in the Cave, almost as if they were glowing. I kept looking at the image and thinking "I really have to keep this scope!!"
One difference is that for me there is a bit of "one-or-the-other" as I am planning to build an observatory and only have so much room. Right now I am trying to decide between several scopes: Takahashi FC-125 and/or FCT-125 on a NJP; TEC200ED on a Losmandy HGM-200/Gemini 2; Cave 12.75" Dr Paul scope on a Schaefer; 18" Starmaster f/4.2. The Starmaster is a definite choice as we have lots more DSO nights than planetary nights here due to seeing issues. Looking at your setup may help in that respect as I intend to have a large deck surrounding the observatory and could incorporate concrete for the extra pier. My original plan was the TEC200ED in a dome and the Starmaster in a rolloff or a roll-away shed. The Cave is such an interesting scope historically and a killer optically. I am not sure how many people would truly appreciate not only how it performs, but the history of it as well. The idea of someone parting it out and putting the mirror into a DOB structure....well, I may just need to find more room.....
Edited by ltha, 22 November 2018 - 08:29 AM.
Posted 22 November 2018 - 08:33 AM
Of course I do have this feeling that if Dr Paul were alive today facing the decision I have he would opt for the TEC......
Posted 22 November 2018 - 08:50 AM
Larry, if you're doing a ROR, I'd say go for double scopes. I'd love to do a ROR, but here there is often just SO much moisture in the air, I need a dome for some level of protection from that.
Posted 22 November 2018 - 10:31 AM
I guess we should have such "problems" Larry.
Interesting as we in our Parks District, just took possession of an AP 1200 GTO for our 8.25" F12.8 achromat. It replaces an up-rated version of the Cave Observatory Series mount, which will be idle....looking for a nice, bigger newt OTA.
And we are a 501.3c organization.
I'm just saying.......
Edited by Jeff B, 22 November 2018 - 10:37 AM.
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